Microtome device



July 2, 1957 M. E. GETTNER ET AL 2,797,616

MICROTONE DEVICE Filed Dec. 27, 1952 3 Sheets-Sheet l July 2, 1957 M. E. GETTNER ET A1.

MICROTONE DEVICE 3 Sheets-Sheet 2 Filed Dec. 27. 1952 main T W WerF- Edf f n, O J wpd. 6 MM2/@uq d A L www m United States Patent M MICROTOME DEVICE Mark E. Gettner, Forest Hills, Leonard Ornstein, New York, and Leroy F. Florant, Brooklyn, N. Y., asslgnors to Joseph Greenspan Application December 27, 1952, Serial No. 328,233

15 Claims. (Cl. 88-40) This invention is that of a microtome that produces specimen sections thin enough for use in electron microscOPy, and also is capable of `cutting thicker sections, for example, for study by a phase microscope. More particularly the microtome of the invention provides by continuous mechanical operation serial sections of a high degree of uniformity of thickness in the individual sections, and from section to section, and having a thickness of under one-tenth, or as low as one-twentieth, micron and even less, as well as from one-tenth to one micron and even thicker, for example, up to ten microns.

The invention also includes novel methods of obtaining individual and serial sections not only of these different ranges of thickness but also in such high degree of uniformity of thickness.

The more extensive use of the electron microscope has emphasized not only the disadvantages encountered in obtaining thin enough specimen sections but also the difficulties met in cutting serial sections of various materials. As an illustration, in other microtomes the specimen block on its return stroke (i. e. back to starting position) is carried past the knife. In that type when the knife lacks adequate sharpness, the section often is not cut off clean at its end. Instead small fragments of embedding material, that should be left behind, are torn from the trailing edge of the block and are held overhanging, toward the block side, the cutting edge of the knife. Then the block in its return stroke catches these overhanging bits and as a result pulls up with them the previously cut section from which they extend. The trough solution adhering to that section then wets the specimen block and is absorbed by the tissue and even by the embedding. Thus, the succeeding cut does not produce a satisfactory section since at least the tissue is scraped off as a sludge.

For electron microscopy, synthetic resins, foi example, polymerized butyl methacrylate, are being increasingly used as specimen embedding material, because of their advantageous electron optical properties. However, due to the resilient character of many of these plastics, the specimen block tends to be compressed slightly during the cutting. Then after passing the knife, because of this resilience the block will extend to its normal length. Consequently, on the return stroke, the block will bear against the back facet of the knife and be recompressed and, due to its resilience, exert a force transversely against the cutting end of the knife. This force against the steel cutting edge bends the very finely thin cutting edge slightly (away from the block), possibly tending to induce cold How, crystallization, or even rupture of the metal structure. Thus, on the next cutting (down) stroke, the specimen block no longer is cut by an ideal edge, but rather by a bent and weakened edge. After a series of such strokes, the cutting edge will even be curled away from the block and result in complete failure to produce good thin-sectioning. Similar difficulty has been observed even with the glass knife.

2,797,616 Patented July 2, 1957 Then also, the variations in speed during cutting accompanying hand operated microtomes produce variations in the stress-strain relationships in the device, and results in erratic behavior when operating at small specimen advances.

These and other shortcomings of prior microtomes are avoided by practising the method of the invention, and because of one or more of the various features of the microtome, or ultra-microtome, of the invention, among which are: (a) operating it by a constant speed motor directly linked to the rst of the rotatable parts of the microtome through a fly wheel coupled with a speed reducer as elements of the microtome; (b) continuously revolving the vise head holding one or more specimen blocks and in off-center vise apertures for them; (c) setting the knife holder at an angle to the cutting side of the plane of revolution of the vise head; (d) a continuously rotating inclined plane (as part of the specimen advancing means) at the other end of the shaft carrying the vise head; (e) means for varying the angle of inclination of the inclined plane to the line of travel of the feed screw, thereby to enable obtaining selection of different thicknesses of sections; (f) a resiliently mounted arm applying a bending moment and axial thrust against the face opposite the advancer nut contact face of the rotating inclined plane; (g) a continuously rotating feed screw, with its axis at an acute angle to the rotating inclined plane, driving the advancer nut along its guide way, and with (h) a blunt nose on the advancer nut continuously moving across the smooth Contact face of the inclined plane thereby continuously to advance the specimen forwardly past the knife; and (i) the nut, driven by the feed screw, being supported between its way carriage and its cap with some room for side to side play thereby to overcome any influence on the forward advance of vise holder by eccentricity that would be set up by any side to side sway of the feed screw.

The invention may be illustrated by, but not restricted to, the embodiment shown in the accompanying drawings, wherein:

Figure l is a plan view of the microtome with its cabinet lid removed.

Fig. 2 is a side to side, vertical section along the line 2"-2 of Figure l, with some rear parts omitted to avoid crowding.

Fig. 3 is a front to rear, vertical section along the line 3 3 of Figure l.

Fig. 4 is a fragmentary, vertical, side to side, section of the arrangement of gears and shifting means to enable driving the feed screw at either (there the low speed drive) of two different speeds.

Fig. 5 is a view like that of Figure 4 but showing the arrangement for the high speed drive.

Fig. 6 is a vertical front to rear fragmentary view along the line 6 6 of Figure 5 to show the clutch engaging teeth of the wheel of a speed reducer in the gear arrangement.

Fig. 7 is a side to side, vertical section of the clutch member.

Fig. 8 is a face view looking into the teeth of the clutch member.

Fig. 9 is a plan view of the swingable base carrying the bearing-mounts for all of the shafts other than that of the feed screw and its driving gears.

Fig. 10 is a fragmentary, vertical section of the arrangement for shifting the position of the swingable base about its pivot.

Fig. 11 is a vertical, side to side section through 011e of the adjustable (as to tightness) bearing and mount supports for the vise head shaft.

Fig. l2 is a fragmentary side view showing the bending moment and axial thrust providing arm and the rotatable inclined plane.

Fig. 13 is a fragmentary horizontal detail partially sectional view through the outer end of the feed screw.

Fig. 14 is a vertical front to rear section through the feed screw, the advancer nut and its retainer cap or bracket.

In the drawings (Figure l), the liexible shaft 20, leading from a constant speed source, such as a constant speed motor (not shown), is coupled at 21 in known manner (details not shown) to the initial drive shaft 22 rotatably suspended between bearings and mounts 24 and 25 immovably rigidly affixed, but removably secured, to the (operations or) swingable base 26 of the microtome. Fly wheel 27 is mounted on shaft 22 on the side of bearing 24 opposite the liexible shaft coupling and is locked in position on that shaft by a set screw running through to the shaft in hub 29 of the y wheel.

Between y wheel 27 and bearing-mount 25, worm 31, of a worm and wheel speed reducer, carried about shaft 22, and separated from that bearing-mount by thrust collar 30 freely meshes with gear wheel 32 which drives the transverse shaft 33 suspended between bearings and mounts 34 and 35 immovably rigidly affixed, but removably secured, to the swingable base 26. Transverse shaft 33 is held against axially longitudinal movement in its bearing-mounts by its shoulder 38 running against one side of bearing 34 and the collar 39 encircling the shaft and fixed to rotate with it by set screw 40. A spiral (or helical) gear 42 is carried on transverse shaft 33 between bearing-mounts 34 and 35 and is locked to rotate with the shaft by known means such as a key in keyways 36 and 37 in registry with one another in the shaft and the gear respectively. The gear 42 is fixed against axially longitudinal movement along the shaft by collar 43 held locked to rotate with the shaft by set screw 44.

The other end of the transverse shaft 33 carries a miter-wheel 45 locked to rotate with it by set screw 46. Miter-wheel 45 enmeshes, and forms a pair of mitergears, with its mate miter-wheel 48 locked to rotate a cantilever shaft 49 by collar 51 and its set screw 52 screwed down against shaft 49 supported in its bearing and mount 53 immovably fixed, but removably secured, to swingable base 26. The free vertical end of collar 51 serves as a thrust bearing by turning against bearingmount 53. Double universal coupling 55 connects shaft 49 to worm shaft 57 carrying worm gear 58 fixed to rotate with shaft 57 by set screw 60 screwed down through hub or collar 62 which serves as a thrust bearing against the rear bearing-mount arm 65. Shaft 57 is rotatable and free for axial movement in bearing arms 64 and 65 respectively spaced away from each end of worm gear 58 and extending upwardly from mount 66 immovably fixed, but removably secured, to the heavy bottom plate 69 of cabinet 70 for the complete microtome.

Front wall 72, right side wall 73, rear wall 74, and left side wall 75 rising together from bottom plate 69 complete the box (indicated as a whole by 76) of the cabinet which in use is closed by lid 77.

Feed screw 80 is rotatably suspended between bearing 81 on mount 82 and bearing 83 on mount 84. Thus, mounts 82 and 84 face, and are parallel to and spaced apart from, one another the distance of the nut advancing operating length of feed screw 80, and are integrally joined at the rear by back plate 85 to form together the feed screw assembly holder 86 immovably fixed, but removably secured, to bottom plate 69. Feed screw 80 can be rotated continuously at either one of two selectable rates by engagement through one or the other of two sets of drive gears with worm gear 58, by the corresponding operation of a speed-selection transmission having the following assembly:

A reduced diameter extension 89 continues axially through bearing-mount 84 to a point (Figures 1, 4 and 5) over a recess 90 in the rear of the upper edge 91 of right side wall 73. Short sleeve 92 has an inside diameter slightly enough larger than the outside diameter of extension 89 to allow it to be slid easily longitudinally forward and backward over extension 89 and to bear on it closely but not tightly. Intermediate sized gear 93 (feed screw high speed drive gear), having a central aperture equivalent to the inside diameter of sleeve 92, is integrally joined to the inner end of this sleeve. Large sized worm wheel 94 (feed screw low speed drive gear), having a similarcentral aperture, is likewise joined to the outer end of sleeve 92. Sleeve 92 and these two gears so joined to it can be considered as a unit and called the transmission 95, and are mounted co-axially on extension 89 with intermediate gear 93 adjacent the outer wall of mount 84. A small length compressible helical coupling spring 96, having an inside diameter equivalent to that of sleeve 92 and outside diameter a little larger than that of sleeve 92, is similarly easily rotatably slipped over extension 89 and in part into a short cylindrical recess 97 constituting a minor and outer' part of sleeve 92 and having an inside diameter only suiciently larger than the outside diameter of spring 96 to enable it to be compressibly received in it.

Then there extends co-axially outwardly from the outer side of worm wheel 94 a short stubby annular ring 98 of the same inside diameter as recess 97 and of an axially measured length less than that to enclose completely spring 96 in its uncompressed normal length when extending out from recess 97. Ring 98 ends in a transversely outwardly extending annular engaging ange 99 forming an annular groove 100 on the outer periphery of annular ring 98. The innermost portion of the thickness of ring 98 is formed as an inner axially directed annular ring of teeth 97a (Fig. 6) with their engaging ends extending to the outer end of ring 98 to present a serrated appearance over a minor part of that end and by encircling the opening to the recess formed by that ring for spring 96.

Then there is also slid on to lead screw extension 89 the toothed clutch coupling 101 having for the major pant of its length, starting from its outer end, the same internal diameter as sleeve 92, and its inner end terminating `in teeth 102, extending toward. and of the same length and thickness as, and adapted to mesh with. the annular ring of teeth 97a extending outwardly from stubby annular ning 98. Teeth 102 are cut through the entire Wall thickness (running radially) of coupling 101.r the teeth 97a in ring 98 have that same thickness (in the radial direction). The balance or minor part 103 of the length of coupling 101 has the same internal diameter as recess 97 in sleeve 92, and forms an inside shoulder 104 in coupling 101 at the junction with the major part which has a smaller inside `diameter as above noted. The length of this minor part .103 of coupling 101 is just a little more than the axial length of teeth 97a so that the end of the part of clutch spring 96 protruding from ring 94, when in uncompressed .state with its inner end touching the inner end of recess 97 in sleeve 92, touches shoulder 104 when teeth 97a and teeth 10.2 are out of mesh and at least clear enough to miss one another when rotated in opposite directions.

Clutch coupling 101 is linked to rotate with extension 89 by key 105 fitted in keyway 106 in the coupling and fitting also into keyway 107 in extension 89. Keyway 107 is long enough axially to allow coupling 101 to be slid inwardly to compress clutch spring 96 until teeth 102 are fully enmeshed with teeth 97a and to be forced axially outwardly until both sets of teeth are at least clear enough to miss one another when rotated in opposite directions.

From the outer end of coupling 101, when spring 96 is compressed for both sets of teeth to be fully enmeshed, extension 89 is threaded to a point on its outer end to leave a lug 108, polygonal (in this embodiment square) in diagonally transverse section and with its diagonal d-imension no greater than the diameter of the bottom of the threads 109 on extension 89.

Shift knob 110 is knurled on its peripheral surface and on one of its sides has a hub with a radially outwardly extending engaging ange 111 (having the same outer diameter as engaging tlange 99) and thereby forming a locking groove 112 of the same diameter at its bottom as the corresponding diameter of locking groove 100 on worm wheel 94. Gear shift lock 113 (Figure 5) is inverted U-shaped from front to rear and running up centrally from the bottom edge in each of its sides has a recess (i114 and 115) of dimension and curvature to conform with half of either of the locking grooves 100 and 112 and to leave a short additional depending extension beyond each end of its semi-circle.

Extension 89 ends in the aperture formed by recess 90 (Fig. 1) in registry with a corresponding recess in the right side wall of lid 77. Hub 116 of detachable turning handle 117 tits through this aperture (including recess 90) with lug 108 of extension 89 in mating tit in recess 11S in hub 116.

In Figure 4, small gear wheel 120, located in recess 121 in the side of bearing-mount 66 facing bearing-mount 84, under and in mesh with worm 58, is integrally joined through a common intermediate hub 124 with large gear 125 so that both are rotatably mounted on shaft 126, The outer end of shaft 126 is supported in bearing-mount 66 and its inner end in hearing 127 in mount 84. Gear 125, by its hub 128 bearing against the radially outwardly extending flange of bearing 127, is spaced away from that bearing a distance su'icient to avoid meshing with spur gear 93 while large wheel 94 is in mesh with worm gear 58.

Visie head drive shaft 130 (Fig. l) is rotatably sus` pend/:d above and horizontally perpendicularly to transverse shaft 33, between bearingmounts 131 and 132, each having its respective horizontally transverse adjustment slit 133 and 134 through one side of the bearing to enable taking up loosencss by the tightening screws 135 and 136 (Fig. ll). Spiral (or helical) gear 137. carried on shaft 130 intermediate bearingmounts 131 and 132 in mesh with spiral gear 42 to be driven by it, is keyed to shaft 130 to rotate it by hey 138 inserted in registered slots (139 in shaft 130 and 140 in gear 137). Geur 137 is locked against slipping axially longitudinally along shaft 130 by set screw 141 screwed down tightly against the shaft through hub 142 of the gear (Figures l and 3).

The vise head end of drive shaft 130 is cio-axially and t frictionally tted (Figs. 3 and .9) into recess 145 in rearwardly projecting hub 146 of circular vise head 147 locke-.t to rotate with shaft 130 by set screw 148 screwed tightly against it through hub 146. Specimen block-holding apertures 149, 14911, 149], 149e are located eccentrically and on different radii of vise head 147. in each of them can be inserted a specimen block 150 (with specimen 151 protruding toward the knife, as in Fig. 9) with each held tightly by a vise screw 152 turned tightly against it (Figures 1 and 2).

The other (or rear) end of drive shaft 130 is frictionally fitted into recess 153 (Fig. 9) in forwardly extending hub 154 of rotatable inclined plane holder 155 and coaxially with it. Set screw 156 in hub 154. locks holder 155 to rotate with shaft 130. Plate glass disk 160 (Fig. l) is held against positioning plugs 161 (three ot' them) extending forwardly from the (vertical) bottom 162 (Fig. l2) of the shallow cupped rear of plane holder 155, solidly embedded in Woods metal (or other melt-able plugging material solid at atmospheric temperature) and with the plane of its smooth exposed face perpendicular to the axis of drive shaft 130 and rearward of the plane of the outer rim 163 of the cupped holder 155 to serve as the rotatable inclined plane.

The horizontal diameter of the inclined plane 165 (i. e.

the exposed face of glass disk is at a small acute angle to the axis of feed screw 80, with its apex nearer the feed screw transmission. Vise head drive shaft 130 has no thrust bearings at its bearing-mounts 1311 and 132 and is given a deliberate and controlled axially longitudinal limited movement by the travel of the blunt nose 167 of advancer nut bracket 168 horizontally across inclined plane (Fig. 1). Advancer nut 170 has on its inner surface threads 171 (Figs. 1, 13 and 14) of the same pitch, form and size as, to mesh with, threads 172 on feed screw 80. To back plate 85 of feed screw assembly holder 86 (Figs. 1 and 14) is firmly secured a waybed 173 having two guide-ways 175 and 176 positioned with horizontal edges of one above those of the other. Nut is strad-dled by its bracket 168 secured by bolts 178 and 179 to carriage 180 which is guided across waybed 173 by upper way-runner 181 secured to the upper end of the carriage by bolts 182 and 183 and lower wayrunner 184 secured t0 the carriages lower end by bolts 185 and 186 (Figure l and 14).

Sway-dampener pins 188 and 189 (Fig. 14) extend in horizontal, diametrically opposed directions from advancer nut 170 and respectively one into a corresponding recess in the inner wall of the nose 1167 of bracket 1618 and the other into such recess in carriage 180. There is room for play between these pins and their recesses in a direction transverse to the direction of travel of nut 170 along the feed screw but none in the direction axially longitudinally along it. Collar 190 (Figs. l, 4 and 5) about feed screw 80 is fixed by set screw 191 to rotate with it at bearing-mount 84. The other end of feed screw 80 (Fig. 13) is reduced in diameter to form shoulder 193 adjacent bearing-mount 82. Sleeve 194 is frictionally tted over this reduced diameter portion, with its radially outwardly turned flange 195 against shoulder 193, and rotatably mounted in bearing 81 with flange 195 against the outwardly turned flange 196 of the bearing.

Axial thrust dauipening and bending moment applying arm (Figs. 1 and 12) is, in this embodiment, an angular lever 200 mounted on horizontal pivot pin 201 supported in trunnions 202 and 203 to rock in a vertical plane parallel to the axis of vise head drive shaft 130 and intersecting the back of plane holder 155 near the end, near universal coupling 55, of its horizontal diameter. Coil spring 205 is held and compressed in the two vertical recesses facing one another, one 206 in the levers short arm 207 near its outer end and the other 208 in swingable base 26. Spring 205 is designed to apply, through tongue 209 near the upper end in the levers long arm 310, against the back of plane holder 155 a force suffcient (a) to give vise head drive shaft 130 a minute definite tilt in a horizontal plane adequate to overcome :any sway that could occur in it from excess clearance in bearings 131 and 132, and (b) to be a positively irnposed backward thrust on shaft 130 sufficient in magnitude to minimize the etect of changes in thrust elsewhere in the system; and without overcoming the deliberate, steady axially longitudinal movement imparted to shaft 130 by passage of advancer nose 167 across inclined plane 165. Trunnions 202 and 203 rise integrally from their anchor base 204 immovably rigidly inserted in, but removably secured to, base 26 by bolt 305 screwed, through washer 312, into a tap in the anchor base.

Swingable (or operations) base 26 (Figs. 1, 2 and 3) rests on three short, level and smooth-topped pedestal lugs 210, 211 and 212 each rising Ito the same height, from bottom 69 of cabinet 70, and each screw-tapped to receive a bolt. Through base 26, between anchor base 204 and bearing-mount 84 (Fig. 9), there passes a vertical, round aperture 213 (called the pivot hole) merely large enough to tallow passing through it a bolt with threads to mesh with those in lug 210. Through pivot hole 213 there is screwed into the threaded depression in lug 210 the lower end of pivot post 260 (Fig. 1) threaded only to a length that goes well into lug 210 and horizontally flanged at a level such that the bottom of the llange 261 will bear down tightly against base 26 and hold 1t motionless when the threaded end has been screwed far enough into lug 210 and then permit base 26 to be swung about an` Unthreaded portion of pivot post 250 snugly fitting in pivot hole 213 when post 251) is unscrewed from the threads in lug 210 insuiciently to be freed from them but enough still to be held securely by them and allow base 26 to be swung along a desired arc. Handle knob 262 permits easy turning of post 250.

T wo vertical elongated slots 214 and 215, called the swing slots, each merely wide enough to allow passing through it a bolt with threads to mesh with those in lugs 211 and 212, and curved to follow its own respective are about a radius centered at pivot hole 213, pass through base 26, respectively near bearing-mounts 34 and 35. Through each swing slot 214 and 215 there is screwed into the threaded depressions in lugs 211 and 212 a securing post 263 and 264 respectively constructed the same as pivot post 260 except that the threads can continue even to the bottom ofthe flange.

Connecting arm 232, immovably rigidly affixed, but removably secured, to base 26 by bolts 218 and 219 at a location intermediate swing slots 214 and 215 and nearer the latter, extends forwardly through a slot in the bottom of front wail 72 to a point beyond the outer edge of setting mound 230 to be described below, and is triangular in vertically transverse cross-section outside of base 26.

A round pivot post 265 is rigidly but removably, sccured to base 26 (Fig. l0) at a point nearest the intersection of front wall 72 land right wall 73 by a screw bolt 266 passed through aperture 267 in base 26 and screwed into the bottom of the post. A closeatopped sleeve 268 of rectangular horizontal cross-section is rotatably mounted on post 250 with the solid portion of its closed top reaching to a height to allow the threaded outer end 270 `of horizontal angle adjustment spindle 271 (see also Figs. l and 2) to engage the initial turns of the threads in a horizontal tap 272 in the closed top portion of the sleeve when the inclined plane 165 is parallel to `the guide- Ways 175 and 176 and scale disk 276 is set at zero. Spindle 271 is supported in an aperture 273 in right wall 73 and aperture 274 in the side of mount 275 integral with that wall. and can be turned by a handle 290 affixed to the lug at its outer end. Thereby the graduated circular scale disk 276, positioned in the recess between wall 72 and mount 275. can be turned to any required setting in relation to the guide mark 277 on top of mount 275.

Section cutting knife 220 (Figs. l and 3) with its cutting edge protruding above the top of horizontally longitudinal slot 22]. of knife holder 222 and its blunt butt 223 resting on the frusto-conical forward ends of blade level adjusting screws 224 and 225 is `held rmly against moving by tightening.' screws 226 and 227. The bottom of knife holder 222 is smooth and level and rests on smooth and level. low setting mounds 229 and 230 on the upper surface of the knife holding platform 231 protruding forward of front wall 72 as an extension of bottoms 69. Connecting arm 232 from base 26 passes in registry through la triangular groove 217, running from front to rear in the bottom of knife holder 222 at a location over setting mound 239 and intermediate its sides, and therebyJ holds knife holder in a position such that the cutting edge 228 of the knife 220 is at an angle of live degrees (apex toward the ywheel side) to the plane described by specimen 151 held on the specimen vise head.

Adjusting screw 233 passes through the threaded horizontal aperture in post 234 rising integnally from platform 231 to enable adjusting the distance of the knife holder over setting mounds 229 and 230. In recess 235, running from front to rear in the underside of platform 231 and intermediate mounds 229 and 230, locking arrn 236 extends from front to rear over shoulder 237 formed by the intersection of locking aperture 238 under the knife holder with the recess and is secured to the bottom by the knife holder nut 239 screwed on to the lower end of stud 240. The other thread of the stud is screwed into tap 241 in the bottom of the knife holder. Knobheaded screw 242 threads through tapped aperture 243 at the front of platform 231 against arm 236.

The open end of trough 245 (for holding the liquid on which the sections are floated) is closed by the midsection of the knife 220 as it is held tightly clamped between the sides and bottom of the open end and the clamping uprights 246 of the clamp arms 247 and 248 pivoted on pins 249 extending into lugs 251 depending from the bottom of the trough, by clamping screws 253 and 254 sorewed down tightly through lugs 25S and 256, projecting from the back of the trough, against the outer ends of the clamp arms.

All bearings supporting rotating shafts are preferably cf porous bearing metal, such as porous bronze, and well lubricated with good quality lubricating oil. The moving and movable ptarts of the transmission, the guide-ways, the feed screw threads, recesses receiving the swaydampener pins 188 and 189, and the surface of the inclined plane, and other moving parts are also well lubricated. All bolts holding any bearing-mounts or other elements on base 26 or on the cabinet bottoni 69 are screwed in tightly to be sure to avoid possibility of vibration of any such part during section cutting operations.

Using a constant speed motor ruiming at S00 R. P. M., gear reducer consisting of worm 31 and gear wheel 32 reduces the speed of transverse shaft 33 to 2() R. P. M. There is no change in speed between shaft 33 and visc head shaft and cantilever shaft 49. When the feed screw transmission is in its low speed setting as in Figure l, the gear reducer consisting of worm 5S and gear wheel 94 reduces the speed of feed screw S0 to four revolutions every ten minutes. Feed screw 80 has 50 threads` per inch. The constant angular velocity applied to the fcc-d screw, by virtue of using a constant speed power source coupled to the initial shaft and its transmission through the transverse and cantilever shafts. produces a constant rate of travel of the blunt nose of the advancer nut across the rotating inclined plane. Since the transverse shaft drives the vise holder drive shaft and, through the intervention of a fixed combination of interlocked constantly rotating elements, also drives the feed screw, there is established a constant ratio between the rate of rotation of the feed screw not only to that of the vise head holding the specimen but also to its rate of advance.

With an angle of fifteen minutes between inclined plane 165 and guide-ways 175--176, the knife 220 will routinely cut sections that are five one-hundredths of a micron thick.

As to operation of the microtorne of the invention. as illustrated by the embodiment shown in the drawings, the several intermeshing gears and thread on the feed screw are so arranged that when the feed screw is in low speed, as in the arrangement in Figures l and 4, rotation of flywheel 27 counter-clockwise will result in counter-clockwise rotation of vise head 147.

A specimen block is inserted in block holding aper- ..re 149 with the specimen protruding forward and fastened there by turning vise screw 152 tichtly against it.

Securing posts 263 and 264 are turned by their knobs to allow swinging of base 26 along the swing slots 214 and 215 when pivot post 250 is loosened sufficiently to allow base 26 to be moved. Angle adjustment spindle 271 is then turned by its handle 290 until the zero point on its scale is at the guide mark 277 on top of mount 275, with inclined plane parallel to the guideways 175- 176. Spindle 271 is then turned till the scale is at the mark equivalent to an angle of fifteen minutes between the inclined plane and the guide-ways. Spindle 271 is held against axially longitudinal motion in its bearings by the thrust bearing 285 (Figs. l, 2 and 10) secured about it and bearing against mount 275. Thus, turning of handle 290 so that threads on the threaded end 270 appear to turn out of the horizontal tap 272 results in swinging base 26 through an arc of fifteen minutes. Then pivot post 260 and securing p-.tsts 263 and 264 are turned to screw their respective flanges down tightly against the top of base 26 to lock it against motion.

The section cutting knife 220 is then mounted with its cutting edge 228 up, between clamping uprights 246 and the open end of trough 245 with its mid-section opposite the open end. Clamping screws 253 and 254 are then turned down until the clamping uprights hold the knife so tightly against the gasket 295 (Fig. l) along the open end of the trough that no liquid can leak out between the knife and the packing. The knife is then placed in slot 221 of knife holder 222 with the trough protruding forward through recess 280 in the front wall 281 of the slot.

Then blade level adjusting screws 224 and 225 are turned for their frusto-conical ends to raise or lower blunt butt 223 of section cutting knife 220 until its cutting edge 228 is at or about the level of the axis of vise head 147, a good level for efficient section cutting. The knife is then locked in place by turning the locking screws 226 and 227 tightly against it. Flywheel 27 is then turned by hand, as can conveniently be done, until specimen 151 is about at the level of the knifes cutting edge 228.

With cutting edge 228 forward of the specimen, adjusting screw 233 is turned to move knife holder 222 over mounds 229 and 230 backward until, by the common practice of observing through a microscope the spacing between the specimen and the knife, it is seen that they are close enough for not too much time to elapse before the knife can begin to cut a section from the specimen. Locking screw 243 is then turned to force locking arm 236 down low enough to lock the knife holder in this setting.

Shift knob 110 (Figs. l and 4) is then turned on threads 109 to move axially toward lug 108 thereby moving away from toothed clutch coupling 101 and in turn releasing the pressure on spring 96. Thus, the latter in expanding pushes coupling 101 outwardly after knob 110 with the teeth 102 of the coupling moving out of mesh with teeth 97a in ring 98 on wheel 94. When knob 110 has been moved far enough for expanding spring 96 to move the interlocked teeth completely out of mesh, handle 117 is turned counter-clockwise turning feed screw 80 likewise and thereby propelling way-runners 181 and 184 together with advancer nut 170 back to the further end of, or starting position on, feed screw 80. At the same time inclined plane holder 155 on its shaft 130 kept moving backward with inclined plane 165 remaining in contact with the blunt nose 167 of advancer nut bracket 168.

Now shift knob 110 is turned in the opposite direction (i. e. clockwise) thereby moving in toward gear wheel 94 and in turn pushing clutch coupling 101 back so that its teeth 102 return into intermeshed engagement with teeth 97a in hub ring 94. Then since clutch coupling 101 is locked by key 105 into rotating engagement with feed screw extension 89, feed screw 80 will be revolved when gear wheel 94 is turned by worm 58 after the motor is started.

The motor running flexible shaft is then started and through the exible shaft turns intermediate shaft 22 counter-clockwise, and the revolution of ywheel 27 on it tends to reduce and eliminate any irregularity. From worm 31 gear wheel 32 reduces the angular Velocity of transverse shaft 33 to one-fortieth that of shaft 22. Shaft 33 transmits this same reduced velocity through the crossed, equal sized spiral gears 42 and 137, to both the rotating inclined plane 165 and vise head 147, and, through the equal miter gears 45 and 48 and double universal coupling, to shaft 57 and its worm gear 58. Gear wheel 94 conveys to feed screw 80 one-ftieth the angular velocity of worm gear 58.

Knife 220 starts cutting a section from specimen 151 as the lower edge of its forward end meets the knifes cutting edge 228 as specimen block is being moved through the nine oclock position of the plane of counterclockwise, continuous rotation by vise holder 147. As the rotation proceeds, revolution of feed screw 80 in its axial stationary position propels advancer nut 170 to the right (toward the gear shift mechanism), which in turn draws the blunt nose 167 of nut bracket 168 across the horizontal diameter of rotating inclined plane 165. Thus, during the rotation, the vise head is being continuously advanced at a calculable, minutely small rate proportional to the tangent of the angle of the inclined plane to the fixed axis of the feed screw. At the same time, the thrust dampening and bending moment applying arm 200, by the resilience of compressed coil spring 205, is continuously imposing backwardly against the inclined plane holder 155 a specific thrust and bending moment of the character described in column 6, lines 38 to 63.

When the cutting of a section is completed, the specimen continues through the lower half of its circular path and rises to progress through the three oclock position. It then passes the knife entirely without contacting it at all because of the distance between them equal to the product of the diameter of that circular path to the tangent of the angle of ve degrees, provided by having set the knife at that angle. This need not be restricted to five degrees and can be any convenient angle sufficient for contact to be avoided completely at the three oclock position.

ln considerable of projects involving microscopical investigation of tissues, study of serial sections is important. For serial sections, the continuous dynamic interrelationship between the elements of this microtome is permitted to go on until the desired number of sections has been cut by this procedure, or until guide-carriage 180 reaches bearing-mount 84. The motor need not then be stopped, and carriage 180 bearing the nut and its bracket are then returned to the starting position in the manner described in column 9, lines 37 to 64. If desired the motor can be stopped after carriage 18 reaches bearingmount 84, and before returning it to the starting position. Cutting these specifications can continue till the number desired is obtained.

If a thinner section is desired of the same or other material, then while the motor is off and the device not in motion, securing posts 263 and 264 are loosened to allow swinging base 26 counterclockwise by turning angle adjustment spindle 271 in the required direction until inclined plane is again parallel to the fixed axis of feed screw 80. Usually swing slots 214 and 215 can be laid out that when base 26 can no longer be moved counter-clockwise, that parallel relationship is reached. Then with the zero point on the scale 276 at the index or guide mark 277 on mount 275, spindle 271 is turned the necessary number of graduations to give the required angle of ten degrees or tive degrees or other amount to enable the desired thinner section to be cut, down to the indicated limit of the device, under five one-hundredths of a micron. Pivot post 260 and securing posts 263 and 264 are then turned in the opposite direction to secure base 26 in the selected position, in the manner described in column 8, lines 62 to 75 and column 9, lines l to 5. Thus far it cannot be stated that one oue-hundredth of n micron or less can be attained for that has not yet been attempted. At the same time there has been no indication as yet that it would be impossible to reach these.

There need be no restrictions to the specific gear ratios of the illustrative embodiment. Others may be used within the nature of the invention.

Likewise, adjustment of the thickness control angle can be made to a size greater than above mentioned to obtain thickness over five one-hundredths of a micron. Then also, for example, to obtain a thickness such as one micron and say up to ten microns, feed screw 80 can be run at its higher speed equal to ten times its lower speed described above. The transmission is used to shift to the high speed gear. Accordingly, gear shift lock 113 is then placed with the flanges at its recesses 114 and 115 setting in locking grooves 100 and 112 thereby to engage wheel 94 with shift knob 110. The latter is then turned to travel outwardly along threads 109 on feed screw extension 89 until spur gear 93 is enmeshed with gear wheel 125. Swingable base 26 is adjusted to the desired angle in the same manner as was done in the low speed. Then the motor is started and the section cutting carried out also as above described. When carriage 180 is to be returned to the starting position, clutch lock 113 can be removed and gears 93 and 94 allowed to return to the same position they had in the description of this operation as carried out in relation to the low speed operation of feed screw 80. Then carriage 170 is returned to the starting position as there described. To start cutting again shift knob 110 is brought near enough to gear wheel 94 to permit reengaging them with clutch lock 113. Then shift knob is turned counter-clockwise until spur gear 93 again is intermeshed with gear 125.

The axial thrust dampening and bending moment applying arm 200 (called briefly the thrust-bending moment arm") preferably applies its force at the position already illustrated, lt may also be applied elsewhere along the same radius so long as the bending moment vector about the axis of inclined plane holder 155 is less than the thrust vector against the holder. This usually occurs in the outer half of the radius. For preferable practical operation, the magnitude of this force applied generally ought to be at least about ten times the magnitude of any thrust elsewhere in the system, the effect of changes in which is to be minimized by this arm 200.

The specimen block apertures 149, 149a, 149b and 149e are placed at different radial distances from the axis of vise head 147 to provide a selection of speeds at which the section can be cut, with all other operating conditions remaining the same. lf some material requires a faster rate, the vise aperture nearer the radius can be used and vice versa.

A constant speed motor of a different rate of revolution than that already illustrated, such as 400 or preferably 300V-350 R. P. M. can be used. Use of the flexible cable presentsl the possibility of having the added advantage of setting the motor on one support, such as a separate table or even a shelf mounted on the wall, and the microtome on another.

Some of the particular types of gears in the illustrative embodiment can be replaced by others. Likewise, other elements or combinations of them in the microtome can be replaced by the equivalent elements or mechanisms or combinations. For example, the thrust-bending moment arm 200 might be replaced by a cylinder open at one end with a suitable helical spring inserted with one end against a closed bottom and piston inserted after it and protruding beyond the open end of the cylinder and having at its outer end a tongue contacting plane holder 155 at the same position as it is contacted by tongue 209. Such cylinder can be supported above base 26 at the elevation of tongue 209 and parallel to arm 207 of lever 200.

While the invention has been described in relation to the specific embodiment illustrated, other modifications and substitutions can be made within the scope of the appending claims, which are intended to include and cover also equivalents of them.

What is claimed is:

l. A microtome comprising a specimen vise-holder mounted on a rotatable vise-holdershaft adapted to be advanced toward a holder for a section cutting knife; a bottom base; a feed screw supported on bearing means mounted on said base, a threaded advancer nut bearing a contact nose and carried on the feed screw in registered threaded relation to its thread; and means for selectively varying the section thickness to be cut by the microtome and comprising a swingable base spaced away from, and supported above, the bottom base and rotatable in parallel relation thereto about an axis perpendicular to both said bases; a member having a plane surface converging at a small acute angle to the axis of the feed screw and adapted to be contacted by the contact nose at a location spaced from the feed screw axis a distance greater than its shortest distance from the plane surface, said plane surface being held by said vise holder shaft which shaft is supported on bearing means mounted on the swingable base and in such manner as to permit continuously advancing and controlled axially longitudinal movement of the shaft away from the feed screw as its rotation propels the advancer nut in a direction axially longitudinally toward the meeting point of the converging plane surface and the feed screw axis.

2. A microtome as claimed in claim l, wherein there is a section cutting knife holder spaced away from the vise head and connected to an extension from the swingable base in front of the vertical plane of the front of the vise head to be movable with the swingable base when it is rotated.

3. A microtome as claimed in claim l, wherein the swingable base is supported above the bottom base by a plurality of lugs rising from the bottom base within the downward projection of the periphery of the swingable base and each to the same height and tapped from its top downwardly to receive the threaded bottom end of a tightening post, one of said lugs serving as the pivot lug; in the swingable base a vertical aperture in registry with the tap in the pivot lug and of a diameter at least just sufcient to permit the passage of a thread titting the tap in that lug; a tightening post to serve as the pivot post and having the outside of its lower end threaded to tit in threaded engagement with the threads in the lug, a flange annularly encircling the post intermediate its ends and having a at bottom at an elevation less than the sum of the thickness of the swingable base and the depth of the tap in the lug but greater than the depth of the tap, the threads at the end of the post rising to a height greater than the depth of the tap and below the flange, whereby on passing the lower end of the post through the aperture in the swingable base and threading its end into the lug, the post flange is drawn down tightly against the top of the swingable base to hold it tightly without vibration; for each other such lug a vertical aperture in the operations base called a swing aperture, each swing aperture having a horizontal curvature the same as that of an arc drawn about the pivot post as a center and by a radius from the pivot post to the middle of the particular swing aperture and radial width equal to the diameter of the pivot aperture, the length of the are of each swing aperture being equivalent to the total angle through which the swingable base needs to lbe rotated to provide the greatest thickness of section to be cut by the microtome; and for each swing aperture a tightening post of the same construction as the pivot post; the lugs being spaced away from the center of the swingable base and so spaced apart from one another to enable said base to be held firmly parallel to the bottom base.

4. A microtome as claimed in claim l, wherein for selectively varying the section thickness to be cut by the microtome, the swingable base is rotated through a Sullicient angle to provide the required section thickness about an axis fixed to the bottom base, and means associated with, and connecting between, both bases to allow selected controlled rotation of the swingable base through the required angle.

5. A microtome as claimed in claim l, wherein there is a specimen vise holder with at least one specimen vise mounted thereon and away from the axis of the shaft holding the member having the plane surface, the vise holder being mounted on the end of said shaft opposite that from the end holding the plane surface, said shaft being mounted for rotation about its axis and in the bearing 13 means; a constant speed motor to provide power to drive said shaft, and means, supported from the swingable base and movable with it, and associated and connected between said motor and shaft, for controlling the rotation of the shaft at a selected constant speed of revolution.

6. A microtome, comprising a rotatable vise-holdershaft mounted for continuous consecutively complete rotation about its longitudinal axis; a specimen-vise-holder mounted on one end of that shaft for rotating the specimen toward the cutting edge of the knife and bearing at lease one specimen-vise with each such vise spaced radially away from the axis of the shaft and being rotatable with the holder about the shaft; rotatable shaft-drivingmeans including a constant speed motor for rotating the vise-holder-shaft continuously at a selected constant speed; shaft-advancing-means having a feed-screw rotatably supported on bearing means for rotation about its axis, a threaded advancer nut carried on the feed-screw in registered threaded relationship to its thread for axially longitudinal movement along the feed-screw on its being rotated; a member having a vertical plane surface converging from side to side at a small acute angle to the axis of the feed-screw and mounted on the vise-holder-shaft rearward of the vise-holder for rotation jointly with that shaft and with the plane of that plane surface perpendicular to it and facing away from and parallel to the plane described by a specimen carried by the vise-holder; rotatable and linking means associated with and connecting with said shaft-driving means and the shaft-advancing means for separately operating the shaft-advancing-means to advance the shaft at a constant rate of advance xed relative to the rate of rotation of the shaft; a contact nose propellable by and along said feed-screw and in a position to be able to contact the plane surface at a location spaced from the feed-screw a distance greater than its shortest distance from 'the plane surface; thereby to enable producing in sequence a series of individual sections having a selected thickness within the range including one micron and down to less than one-twentieth of a micron and yet with uniform thickness within the individual sections and from section tto section in each series.

7. A microtome comprising a rotatable vise-holder-shaft mounted for continuous consecutively complete rotation about its longitudinal axis and supported on bearing surfaces that allow its controlled gradual axially longitudinal advance toward the knife; a specimen-vise-holder mounted on one end of that shaft for rotating the specimen toward the cutting edge of the knife and bearing at least one specimen-vise with each such vise spaced radially away from the axis of the shaft and being rotatable with the holder about the shaft; rotatable shaft-driving-means including a constant speed motor for rotating the vise-holder-shaft continuously at a selected constant speed; shaft-advancingmeans associated with and connecting with said viseholding shaft at a location rearwardly away from the vise-holder, gradually to advance that shaft axially longitudinally toward the knife-holder, and including a member having a plane-surface mounted on the other end of that shaft for rotation jointly with it and with the plane of the plane surface facing away from the shaft and perpendicular to its axis and parallel to the plane described by the rotation of a specimen carried by the vise-holder; a rotatable advancer-feed-screw mounted for continuous rotation about its axis and spaced rearwardly of the plane surface; and a blunt-nosed advancer-nut mounted on the feed-screw to be propelled longitudinally axially in relation to it by the rotation of the screw, the axis of the latter being positioned at an acute angle relative to the plane surface for the blunt-nose to be able to contact that surface and to propel the nut with its nose contacting that surface from one end of its horizontal diameter to the other while rotation of the vise-holder-shaft rotates the plane surface, and thereby advancing that surface and the vise-holder-shaft on the bearing surfaces supporting it; and rotatable means associated with and connecting with said shaft-driving means and the shaft-advancing means for separately operating the shaft-advancing-means to advance the shaft at a constant rate of advance fixed relative to the rate of rotation of the shaft; thereby to enable producing in sequence a series of individual sections having a selected thickness within the range including one micron and down to less than one-twentieth of a micron and yet with uniform thickness within the individual sections and from section to section in each series.

8. A microtome as claimed in claim 6, wherein the viseholder has more than one specimen-vise with each located respectively at a different radial distance from the axis of rotation of the vise-holder-shaft.

9. A microtome as claimed in claim 7, wherein the means for separately operating the shaft-advancing-means are associated and connected with the vise-holder-shaft driving means by rotatable means that rotate the feedscrew at a selected constant rate of rotation fixed relative to the constant rate of rotation of the vise-holder-shaft.

l0. A microtome as claimed in claim 9, wherein the means for separately operating the shaft-advancing-means has speed changing means adapted to enable selectively changing the ratio of the constant rate of rotation of the vise-holder-shaft to the constant rate of rotation of the feed-screw from one ratio to another ratio between them,

ll. A microtome comprising a specimen holder vise head mounted on a rotatable vise-holder-shaft for rotation with it about its axis, a holder for a specimen cutting knife spaced away from said shaft and adapted to hold the cutting edge of a specimen cutting knife in position to cut a section from a specimen held in the vise head as it carries the specimen with an end exposed to be cut by the knife; means continuously gradually to advance the vise-holder-shaft axially longitudinally toward the knife holder, said advancing means including a feed-screw rotatable about its axis, a member having a plane surface rotatable with, and perpendicular to, and facing away from, the vise-holder-shaft and converging at a small acute angle to the axis of the feed-screw, and a contact nose linked to the feed-screw by means propellable by the rotation of the screw, said nose being thereby adapted to be able to contact the plane surface at a location spaced from the feed-screw a distance greater than its shortest distance from the plane surface whereby` upon the rotation of the feed-screw, the contact nose is propelled longitudinally parallel to the screw and contacts the plane surface along its horizontal axis and continuously gradually advances the vise-holder-shaft; and a constant speed motor and means connected therefrom to operate the holder-shaft at a constant rate of rotation, and, connecting with said first means, other means to operate the feed-screw at a constant rate of rotation and in a fixed ratio to the rotation rate of the holder-shaft.

l2. A microtome as claimed in claim ll, wherein there is a resilient axial-thrust-dampening and bending-momentapplying arm positioned to contact the back of the rotatable member having the plane surface and to apply and exert a resilient pressure against said rotatable member, when it is rotating, and at a location on the back of that member radially removed from its axis and at a distance therefrom sufficient for it to overcome any sway that could occur from excess clearance in its shaft mounting and to minimize changes in thrust in that rotating system.

13. A microtome as claimed in claim l1, wherein the member having the plane surface and rotatable with the vise-holder-shaft, comprises a shallow cup-shaped holder with its open end facing the feed-screw and perpendicular to, and co-axial and rotatable with, the vise-holder-shaft; and a sheet material with a highly smooth plane surface is rigidly fixedly held embedded in the cup-shaped cavity of the holder, in an embedding material solid at atmospheric temperature, and with its plane surface exposed.

l4. A microtome as claimed in claim 13, wherein the sheet material is plate glass with a polished surface exposed.

15. In a microtome having a specimen vise holder mounted on a vise-holder-shaft supported to permit it to be advanced toward a holder for a section cutting knife, means for advancing said shaft toward the knife-holder and comprising a feed-screw rotatably supported on bearing means for rotation about its axis, a threaded advancer nut carried on the feed-screw in registered threaded relationship to its thread for axially longitudinal movement along the feed screw on its being rotated; a member having a vertical plane surface converging from side to side at a small acute angle to the axis of the feedscrew and mounted on the vise-holder-shaft rearward of the viseholder for rotation jointly with that shaft and with the plane of that plane surface perpendicular to it and facing away from and parallel to the plane described by a specimen carried by the vise-holder; a rigid guide-way spaced away from and supported in straight line parallel relationship to the feed-screw axis; a bracket straddling the advancer nut and supported by guide-way runner means fitted in snug registry with the guide-way for slidable movement along its length; a Contact nose on the bracket in a position to be able to contact the plane surface at a location spaced from the feed screw a distance greater than its shortest distance from the plane surface; the bracket being linked by loosely fitting linking means to the advancer nut to move with it in the same direction as the nut moves along the feed-screw, when the latter is rotated, and by said linking means adapted to avoid any influence on the bracket by any swaying motion of the feed-screw and advancer nut transverse to the feed screw axis.

References Cited in the tile of this patent UNITED STATES PATENTS 325,722 Bausch Sept. 8, 1885 1,026,280 Ott May 14, 1912 FOREIGN PATENTS 27,430 Great Britain Dec. 29, 1898 8,258 Great Britain Apr. 19, 1899 400,691 Great Britain Nov. 2, 1933 456,164 Canada Apr. 26, 1949 654,123 Great Britain June 6, 1951 

